The main obstacles to the use of hydrogen as an energy carrier are the storage, transport, distribution and choosing the ideal system to produce energy through the same. Among the possible systems for producing energy from hydrogen there are fuel cells, such as those of a PEM-type (proton exchange membrane) that function efficiently converting hydrogen (properly provided) and oxygen from the air in energy and water as a by-product, this being environmentally benign. For these reasons, the development of systems capable of efficiently storing and transporting hydrogen is essential in the field.
Hydrogen can be stored in different ways:                i) compressed        ii) liquefied        iii) by adsorption on porous materials processes, and        iv) forming chemical bonds in metal hydrides, complex hydrides or organic compounds.        
Among the metal hydrides mentioned in iv) there are a large number of compounds capable of releasing hydrogen by catalyzed hydrolysis. Among these metal hydrides, there are magnesium hydride (MgH2) (M. H. Grosjean, M. Zidoune, I. Roué, J. Y. Huot, Int. J. Hydrogen Energy, 2006, 31,109) and calcium hydride (CaH2) (M. Q. Fan, F. Xu, L. X. Sun, Int. J. Hydrogen Energy, 2007, 32.2809).
Among the complex hydrides mentioned in iv) there are borohydrides such as lithium borohydride (LiBH4) (Y. Kojima, Y. Kawai, M. Kimbara, H. Nakanishi, S. Matsumoto, Int. J. Hydrogen Energy, 2004, 29, 1213), potassium, rubidium and cesium borohydrides (KBH4, RbBH4, CsBH4 respectively) (C. Cakanyildirim, M. Gürü, Int. J. Hydrogen Energy 33, 2008, 4634-4639) and sodium borohydride (NaBH4).
Among the hydrides capable of releasing hydrogen by a hydrolysis reaction, sodium borohydride (BHS) has been widely studied due to its high content of hydrogen and its great stability in basic solutions at room temperature. Recent reviews include a wide literature on it (B. H. Liu, Z. P. Li, J. Power Sources 187, 2009, 527-534; U. B Demirci, O. Akdim, J. Andrieux, J. Hannauer, R. Chamoun, P. Miele, Fuel Cells 3, 2010, 335-350). It is known that hydrogen free of carbon monoxide can be obtained by hydrolysis of alkaline solutions of BHS in the presence of certain catalysts using the following equation:NaBH4+(2+X)H2O→NaBO2.XH2O+4H2+Q  (1)wherein X=2-4(H. I. Schlesinger, H. C. Brown, A. E. Finholt, J. R. Gilbreath, H. R. Hoekstra, E. K. Hyde, J. Am. Chem. Soc, 75, 1953, 215-219; J. C Walter, A. Zurawski, D. Montgomery, M. Thornburg, S. Revankar, J. Power Sources 179, 2008, 335-339).
To catalyze these types of reactions, the cobalt boride is a known catalyst and not as expensive as precious metals (C. Wu, F. Wu, Y. Bai, B. Yi, H. Zhang, Materials Letters 59, 2005, 1748-1751). For certain applications, it is preferred to support the catalyst on suitable supports like Ni foam (J. Lee, K. Y. Kong, C. R. Jung, E. Cho, S. P Yoon, J. Han, T. G Lee, S. W. Nam, Catalysis Today 120, 2007, 305-310). The recent literature contains a large number of examples of systems for hydrogen production by catalyzed hydrolysis of sodium borohydride (S. J. Kim, J. Lee, K. Y. Kong, C. R Jung, I. G Min, S. Y. Lee, H. J. Kim, S. W. Nam, T. H. Lim, J. Power Sources 170, 2007 412-418; P. P. Prosini, P. Gilson, J. Power Sources 161, 2006, 290-293; D. Gervasio, S. Tasic, F. Zenhausern., J. Power Sources 149, 2005, 15-21; R. Oronzio, G. Monteleone, A. Pozio, M. De Francesco, S. Galli, Int. J. Hydrogen Energy 34, 2009, 4555-4560; Q. Zhang, G. M. Smith, Y. Wu. Int. J. Hydrogen Energy 32, 2007, 4731-4735). For any design capable of producing hydrogen based on catalyzed hydrolysis of a complex hydride, such as it may be preferably sodium borohydride, that wants to adapt to a fuel cell is critical to ensure a hydrogen production at constant rate, at a value that will depend on the conditions of the same (power and voltage). Given the exothermic nature of the reaction (equation (1)), the constancy of rate requires the environment in which the reaction proceeds to be as isothermal as possible (B. H. Liu, Z. P. Li, S. Suda, J. Alloys and Comp. 468 (2009) 493-493). The temperature control can be achieved with a suitable system/reactor design. Said design may vary from a simple cooling of the reactor to the continuous flow of reactants and products as a means of removing the heat generated during the reaction (S. J. Kim, J. Lee, K. Y. Kong, C. R Jung, I. G Min, S. Y. Lee, H. J. Kim, S. W. Nam, T. H. Lim, J. Power Sources 170, 2007, 412-418).
To optimize the conditions for hydrogen production, the total conversion of the BHS and the gravimetric storage capacity of the fuel+catalyst system should be maximized. While the literature provides examples where high values of hydrogen gravimetric storage capacity are obtained (B. H. Liu, Z. P. Li, S. Suda, J. Alloys and Compd. 468, 2009, 493-493; D. Hua, Y. Hanxi, A. Xinping, C. Chuansin, Int. J. Hydrogen Energy 28, 2003, 1095-1100; Y. Kojima, Y. Kawai, H. Nakanishi, S. Matsumoto, J. Power Sources 135, 2004, 36-41), these systems do not produce hydrogen at a constant rate, which is considered highly necessary for the fuel cell.
In regard to the devices commonly used for hydrogen production, some reviewed patent applications describe systems based on the catalyzed hydrolysis of sodium borohydride at high pressures (Hou, X CN101397124-A; Jorgensen SW, US 2004052723-A1; Toyota Chuo Kenkyusho KK, JP2003004199-A), implying that the hydrogen produced must be properly dispensed through a valve, having problems as it is dispensed due to the pressure drop. This obviously affects the production of hydrogen at a constant rate.
As for the catalysts used in the production of energy using hydrogen in fuel cells, according to a 2010 review (U. B Demirci, O. Akdim, J. Andrieux, J. Hannauer, R. Chamoun, P. Miele, Fuel Cells 3, 2010, 335-350) in recent years papers have been published that maximize the activity of said catalysts, but there are little activity data in experiments of long duration, or on the possibility to reuse the catalyst several times.
To solve these problems encountered in the field, the present invention proposes a process of continuous production of hydrogen at constant rate and temperature, based on adding a source of hydrogen as a complex hydride that acts as fuel, preferably sodium borohydride, stabilized in a hydroxide solution, preferably sodium hydroxide, over a cobalt boride (CoB) catalyst, preferably supported on nickel foam. The control of the reaction temperature and rate in this process, which as mentioned are critical to optimize the conditions for hydrogen production is based on controlling the rate of addition or aggregation of the fuel solution to the catalyst. It is also essential to consider the concentration of the hydride in the stabilized solution used as fuel.
Based on theoretical considerations, the present invention has optimized the production of H2 controlling both conditions, concentration of the complex hydride in the fuel solution and the rate of addition of the same, under conditions of excess catalyst, so that it has managed to maximize the total conversion of the complex hydride, especially in the case of sodium borohydride, into H2 and the gravimetric storage capacity of the fuel+catalyst system with constant rates of production of hydrogen, said rates being adapted to the fuel cell, preferably of PEM-type to which hydrogen is intended.
On the other hand, the invention proposes a hydrogen production facility comprising a device, a semi continuous reactor, very simple in design and that can be built with lightweight materials, having portable applications in mind. Some works previously disclosed in the field of industrial protection (Wang Y, CN1458059-A; Jorgensen SW, US 2004052723-A1; and Braun J, WO 2009086541-A1) include additional components in the design for temperature and agitation control, which makes the device a more complex system. None of the known documents proposes to maximize the conversion of the hydride or the gravimetric storage capacity of the fuel-catalyst system simultaneously with the production of hydrogen at a constant rate.
In addition, we propose here a novel method and not reported so far to reactivate the CoB catalyst, preferably supported on nickel foam, for subsequent reuse thereof several times in the process of hydrogen production. This method is based on two fundamental steps or stages: i) washing and ii) chemical reactivation. Other methods of reactivation proposed in the literature include a single washing step (J. H. Kim, K. T. Kim, Y. M Kang, H. S. Kim, M. S. Song, Y. J. Lee, P. S. Lee, J. Y. Lee, J Alloys and Compd. 379, 2004, 222-227 and U. B. Demirci, F Garin, J Alloys and Compd., 2208, 5, 1), but washing as the only step does not allow recovering the catalyst activity that has long been used and stored without further care. The step of chemical reactivation allows the reuse of the catalyst that has already been used and left in the highly corrosive reaction mean for several months, which is a further innovation of the present invention.